Metallurgical scavenger and method of making same



Patented June 23, 1936 PATENT OFFlCE METALLURGICAL SCAVENGER'AND DI ETHOD OF MAKING Charles J. Kinzie, Niagara'Falls, N. Y., assignor SAME to The Titanium Alloy Manufacturing Company, New York, N. Y., a corporation of Maine No Drawing. Application December 2, 1933. n

Serial No. 700,731

18 Claims.

My invention relates to improved forms of compounds employed in metallurgical operations for cleansing and improving metals when added thereto while such metals are in a molten state,

such compounds being adapted to combine chemically with the impurities of the molten metals to form compounds including slags that rise to the surface of the underlying molten metal. More particularly, the objects of my invention are, among other things, the production of mechanical mixtures of titanium carbide or zirconium carbide or both with iron in briquetted forms that are especially adapted for introduction into the molten metal bath to cleanse such molten metal of its impurities.

In the treatment of metals, such as molten iron or steel, with minor quantities of other metals or alloys or compounds thereof to eflect either an alloying of the major with the minor metal or a cleansing of the major metal by virtue of the scavenging effect of the minor metal upon impurities in the major metal, it has formerly been the practice to use so-called alloys prepared principally in the electric arc furnace, such as alloys of titanium with iron, or alloys of zirconium with iron.

In the preparation of titanium alloys, such as ferro-carbon-titanium made according to United States Patents to Rossi and Meredith No. 1,039,672 of September 12, 1912 and No. 1,094,022 of April 21, 1914, it has been found diflicult or impossible to have the carbon content as low as desired due mainly to the fact that the fused charge tends to take up and become supersaturated with carbon; the'result is that commercial ferro-carbon-titanium as prepared according to these patents contains about twice as much carbon as would be combined with titanium as the carbide (TiC) The following is a typical analysis of the ferro-carbon-titanium of commerce:- Titanium about 16%, carbon about 8% and the balance about 76% comprising chiefly iron and other substances.

Although this ferito-carbon-titanium is entirely suitable for many purposes, it has long been recognized that if an alloy containing about 16% of titanium, 4% or less of carbon with the balance iron could be produced, it would find extended application in the treatment of certain grades of iron where it is required that the carbon be kept as low as possible, and in which the normal content of carbon in ferro-carbon-titanium is objectionable.

So far attempts to produce by fusion or melting in the electric arc furnace, a ferro-carbontitanium alloy containing, say 16% of titanium and less than .6 carbon, have not been successful, and at present it is not indicated that an alloy containing the desired low percent of carbon may be obtained by this Rossi and Meredith process which specifies, among other things, that suflicient carbon should be present to ensure such uncombined carbon content as may be desirable. I In working on this problem I conceived the idea of preparing a mechanical mixture of titanium carbide, TIC, with iron, in form 01 briquettes in such a manner as to produce suitably sized briquettes containing for example, the following constituents:

' Per cent Tita u 16 Carbon- 4 Iron (and others) -i 80 My belief is predicated on the fact that in dissolvingv the usual form of ferro-carbon-titanium in acids, about one-half the carbon remains as a black residue, while approximately one-half the carbon content passes off directly as agas. Titaniu'm'carbide (TiC) as well as zirconium carbide (ZrC), dissolve to a perfectly clear solution in acids, but if dissolved or free carbon be present, such carbon remains as a black residue.

Therefore I understand that in scavenging or in alloying operations, the carbon combined with the titanium, etc. probably is yielded readily and passes off as a gas, while the free carbon may undesirably remain in the metal treated. Either titanium or zirconium carbide has too high a melting point and dissolves too slowly in the metal bath to serve effectively as scavengers or as alloying substances, and, if used as a powder, the loss would be excessive.

According to my invention I have discovered that by preparing a briquette of the titanium carbide and iron, a metallurgical scavenging product is produced which remains in the molten bath,

and, as the iron melts, the carbide particles act' upon the impurities, and a scavenging efiect is produced withnut the incidental introduction of excess carbon which accompanies the use of ferrocarbon-titanium prepared by the Rossi and Meredith methods.

In preparing my new product, I crush the carbide of titanium or zirconium to suitable fineness and then mix .it in suitable proportion with iron metal powder,using a small amount of a suitable bond such as a sodium silicate solution,

natural gums, glue, dextrine and synthetic plastic or resinous materials, forming a mix of suitable consistency for pressing, and then compact same by pressing to form a suificiently hard, coherent mass consisting of a mechanical mixture of, for instance, titanium carbide, iron and a binder substance. Zirconium carbide may be substituted for the titanium carbide with similar results.

The following example will serve to illustrate how a titanium carbide iron briquette is made:-

Ezample A.Titanium carbide is crushed to obtain a product passing through' forty mesh, while the iron is prepared to pass 40 mesh. The iron is preferably prepared by the sponge iron process by heating a mixture of parts of -10 mesh magnetite am 60 parts of 20 mesh coal under reducing conditions at temperature of about 1050 C. for six hours, cooling the charge out of contact with air, and then crushing to 40 mesh and removing the excess carbon and other substances from the iron by suitable concentrating treatment, such as magnetic separation.

.A mixture is then made as follows (parts by weight) Parts 40 mesh titanium carbide 100 40 mesh iron metal 400 Sodium silicate solution 1.30 sp. gr 75 Total -575 suflicient to accomplish desired results.

The grain or granule size of raw materials used in process of making the briquettes may vary widely as also the proportions of titanium carbide and iron. In this example the product contained approximately:

Percent Titanium 15.13 Carbon 3.78 Iron and other compounds 75.72 Sodium silicate bond 5.37

Percent Zirconium content 15.8 Carbon 2.20 Iron and others 76.9 Sodium silicate bond 5.1

An example of my methods of making a titanium carbide briquette by the use of an alkali zirconium silicon citrate as a bond is now given.

Example B.--100 parts of titanium carbide (-40 mesh) and 400 parts of iron metal particles (-40 mesh) are dampened with 35 parts of the citrate of sodium zirconium silicate solution such as is set forth in my pending application for patent Serial No. 623,605 filed July 20, 1932, which has approximately the following composition:

This charge is mixed well to form a damp mixture, and is then pressed into form and dried; an addition of water may be made to the charge if required.

A titanium carbide iron briquette made from above proportions of titanium carbide and iron using 35 parts of the citrate compound would have the following composition after drying:

Percent Titanium 15.8 Iron 78.4 Carbon 3.9 Citrate bond 1.9

The following is an example using zirconium oxychloride as a bonding material.

Example C.-A charge is made up containing the following ingredients:

Parts by weight Titanium carbide (40 mesh) 100 Metallic iron (-40 mesh) 400 ZrOCl2+3H2O 20 The charge is mixed with just enough water to form a paste, and then the mass is stiffened by addition of a suitable precipitant for the zirconium, such as, ammonia or phosphoric acid. The stiffened charge is then formed into shape and dried to form a coherent briquette.

Such briquette would contain approximately the following:

. Percent Titanium; 15.9 Iron 78.4 Carbon 3.9 Balance. ZIO2, etc. bond 1.8

The following example is given to illustrate the production of a titanium carbide-zirconium carbide briquette.

Example D.A charge is made up of approximately the following ingredients:

- I Parts by weight Titanium carbide (-40 mesh)- Zirconium carbide (40 mesh) 50 Metallic iron (-40 mesh) 415.5 1.3 5;). gr. sodium silicate solutionl 75 The charge is mixed to damp consistency and pressed into shape and dried.

The composite briquette will have the following approximate composition:

The titanium carbide referred to in the foregoing examples is produced by reduction of titanium oxide (TiOz) in presence of carbon in an electric furnace, having only enough carbon in thecharge to form TiC.. Some carbon of course will come from the electrodes and furnace lining material and the initial charge should be so proportioned as to allow for this. During the run in an electric arc type furnace, the contact with air should be avoided in order to prevent the absorption of nitrogen with resultant formation of nitrogen compounds. The charge is cooled in the furnace in which it was formed, and is then. cleaned from foreign material, unreduced charge, etc., and is thereafter crushed and pulverized to suitable fineness, 40 mesh for instance. mately the following analysis: Titanium 79%? carbon 19% and other compounds 2%.

Zirconium carbide is made in substantially the same manner by using either zircon (ZrSiO4) or ZrOz as the starting material. Such zirconium carbide has approximately the following analysis: Zirconium 86%; carbon 12%; and other compounds 2%.

I do not wish to confine my methods to the cold or low temperature forming of the briquettes, since a mechanical mixture of the titanium .carbide and iron powder could be heated in a reducing atmosphere to a temperature sufficiently high to cause the iron to sinter and thus bond the titanium carbide particles and iron without employing a'bonding material.

Again a low melting point metal, such as zinc, tin, etc. might be incorporated in small amounts, and by heating the mixture to, or slightly above, the melting point of the soft metal a bonding of my briquettes may be effected.

I do not wish to be limited to the press method of producing the briquettes, because suitable mixtures could be extruded.- into rods of 'any suitable size and 'shape, dried and hardened in any suitable manner. Suitable products could be made by hand-shaping to the desired size and shape.

Though I have described the formation of briquettes of titanium carbide and/or zirconium carbide mixed with iron, other metals besides iron might be used in the briquette as I have indicated, and such briquette could be used in alloying with or otherwise treating a bath of molten metal such as is used together with the titanium and/or zirconium carbiderbriquette for scavenging elfects.

I claim as my invention:-

1. A method of making metallurgical scavengers containing a carbide of a metal of the group consisting of titanium and zirconium mixed with another metal as major ingredients thereof, which comprises intimately mixing said ingredients in finelydivided form with a bonding agent to form a coherent mass of moldable con sistency, and then briquetting same.

2. A method of making metallurgical scaven gers containing a carbide of a metal of the group Such titanium carbide has approxi- Y consisting of titanium and zirconium mixed with iron as major ingredients thereof, which comprises intimately mixing said ingredients in finely-divided form with a bonding agent to form a coherent mass of moldable consistency, and 5 then briquetting same.

3. A method of making metallurgicai\scavengers containing a carbide of a metal of the group consisting of titanium and zirconium mixed with another metal as major ingredients thereof, which comprises intimately mixing said ingredients in finely-divided form with a bonding agent to form a coherent mass of moldable consistency, forming briquettes of said mixture, and

drying same. 15

4. A method of -making metallurgical scavengers containing a carbide of a metal of the group consisting of titanium and zirconium mixed with iron as major ingredients thereof, which comprises intimately mixing said ingredients in finely-divided form with a bonding agent to form a coherent mass of moldable consistency, forming briquettes of said mixture, and drying same.

5. A method of making metallurgical scavengers containing titanium carbide mixed with another metal as major ingredients thereof, which comprises intimately mixing said ingredients in finely-divided form with a bonding agent to form a coherent mass of moldable consistency, and then briquetting same.

6. A method of making metallurgical scavem gers containing titanium carbide mixed with iron as major ingredients thereof, which comprises intimately mixing said ingredients in finely-divided form with a bonding agent to form a 00- 35 herent mass of moldable consistency, and then briquetting same.

7. A method of making metallurgical scaife'ngers containing zirconium carbide mixed with another metal as major ingredients thereof, which 40 comprises intimately mixing said ingredients in finely-divided form with a bonding agent to form a coherent mass of moldable consistency, and then briquetting same.

8. A method of making metallurgical scavengers containing zirconium carbide mixed with iron as major ingredients thereof, which comprises intimately mixing said ingredients in finely-divided form with a bonding agent to form acoherent mass of moldable consistency, and then briquetting same.

9. A methood of making metallurgical scavengers containing titanium carbide and zirconium carbide mixed with another metal as major ingredients thereof, which comprises intimately mixing said ingredients in finely-divided form with a bonding agent to form a coherent mass of moldable consistency, and then briquetting same.

engers containing titanium carbide and zirconium carbide mixed with iron as major ingredi-' ents there0f,which comprises intimately mixing said ingredients in finely-divided form with a bonding agent to form a coherent mass of moldsilicate solution (sp. gr. 1.30) to form a coherent 75 10. A method of making metallurgical scavmass of moldable consistency, and then briquetting same.

12. A method of making metallurgical scavengershaving a relatively low carbon content and containing zirconium carbide mixed with iron as major ingredients thereof, which comprises intimately mixing 100 parts of finely-ground zirconium carbide and 431 parts of finely-ground iron moistened with about 75 parts of sodium silicate solution (sp. gr. 1.30) to form a. coherent mass of moldable consistency and then briquetting same. a

13. A briquette consisting of a coherent mechanical mixture of finely-ground carbide of a metal of the group consisting of titanium and zirconium, another metal and a bonding agent.

14. A briquette consisting of a coherent mechanical mixture of finely-ground carbide of a metal of the group consisting of titanium and zirconium, iron and a. bonding agent.

15. A briquette consisting of finely-ground car= bide of a metal of the group consisting of titanium and zirconium and iron bonded together by sodium silicate.

16. A briquette consisting of finely-ground titanium carbide, zirconium carbide, and iron bonded together by sodium silicate.

17. A briquette consisting of finely-ground titanium carbide and iron, said carbide comprising one molecule of carbon to one molecule of titanium and a bonding agent.

18. A briquette consisting of finely-ground zir coniumfi carbide and iron, said carbide compris= 15 ing one molecule of carbon to one molecule of zirconium and a bonding agent.

7 CHARLES J. KINZIE. 

